Stephanoidea

Stephanidae Temporal range: Cenomanian–Recent PreЄ Є O S D C P T J K Pg N
Stephanus serrator
Scientific classification
Kingdom:	Animalia
Phylum:	Arthropoda
Class:	Insecta
Order:	Hymenoptera
Superfamily:	Stephanoidea
Family:	Stephanidae Leach, 1815
Subfamilies
see text

The Stephanidae, sometimes called crown wasps, are a family of parasitoid wasps placed in the superfamily Stephanoidea, which has at least 345 living species in 11 genera. The family is considered cosmopolitan in distribution, with the highest species concentrations in subtropical and moderate climate zones. Stephanidae also contain four extinct genera described from both compression fossils and inclusions in amber.

Stephanids are noted for their ocellar corona, a semicircular to circular set of projections around the middle ocellus, forming a "crown" on the head. Only stephanids and the similarly old Hymenoptera family Orussidae have ocellar coronae, and it is uncertain if they developed the structure separately or if a common ancestor of both developed it and it was then lost in all but the two families. Weakly developed grooves starting at the base of the antennae and extending past the eyes to the back of the head capsule are present. This feature is seen more developed in hymenopteran families in which the adults emerge from pupal chambers in wood. All genera of Stephanidae have a pronotum that is modified to some extent. They bear highly modified hind legs, with a swollen hind femora that has large teeth on the underside, and the tibiae have a tip end that widens distinctly. The largest species, reaching up to 35 mm (1.4 in) in length, are found in the genus Megischus. Stephanids are noted as parasitoids of xylophagous beetle larvae, with a majority of the stephanids coming from the families Cerambycidae and Buprestidae, though some Curculionidae and occasional hymenopteran hosts are taken. One species, Schlettererius cinctipes, is a known parasitoid of horntail wasps, and has been introduced to Tasmania as a biological pest control agent. Members of the genus Foenatopus are parasitoids of Agrilus sexsignatus, wood-boring beetle larvae found infesting eucalyptus in the Philippines. The rate of parasitism for an A. sexsignatus population was recorded to vary from only 2% up to 50% of the population.